I got aproximately 250rds. of 5.56x45 ammo for $10 from a local gun dealer who was going out of buisness. Most of the ammo was Lake City 55gr. M193 dated in the 80's. But I also dicovered two odd looking rounds. The haed stamp reads TW and 73, it has a roundish flat nose and is fmj. Any body know what this counld be?